You don't exist! I apologize for taking koju's(
http://www.fairiesvampires.com/profile/koju) zealous statement, but the term bitten is used so incorrectly! The change is a blood transfusion, thus the vampire blood takes over the host body and most of the time just kills the host. Sometimes, rarely though, the change be complete, and the host becomes a vampire.
The change is usually excessively painful, but a Grigori(the biblical term for Old Ones) can manipulate the change so instead of pain, you could feel nothing during it. Also, a Grigori can manipulate the metamorphisis to make the host more likely to change. I doubt a real Grigori will be willing to change a human into a Sanguinarian in the first place, so why even bother?
For those Twilight fans who think the change is from a venom when bitten, that is inaccurate. There is no species on that changes with venoms(or toxins) that alters the DNA of a species, as Jim has said before. Generally, venom is injected by such means as a bite or a sting, venomous, refers to animals that deliver venom in self-defense or in hunting, not to alter the species's DNA into a near-replica of itself. Even so, in this case, it cannot be described as venom.
Venom
a poison wielded by an animal; felling or speech marked by spite or malice
en.wiktionary.org/wiki/venom
Poison
any substance that causes injury or illness or death of a living organism
If the change is painful, but does not really injure the organism, then it cannot be classified as a poison. Therefore, it also cannot be classified as a venom.
In conclusion, the change is really a blood transfusion. Also, the change is not a venom. The term "bitten" is incorrect. Please use "changed" or some other term that fits the case.
Vescere bracis meis(latin) posuers(English)!
-Gabriel